Google Cloud Professional Cloud DevOps Engineer — Question 29

You support a high-traffic web application with a microservice architecture. The home page of the application displays multiple widgets containing content such as the current weather, stock prices, and news headlines. The main serving thread makes a call to a dedicated microservice for each widget and then lays out the homepage for the user. The microservices occasionally fail; when that happens, the serving thread serves the homepage with some missing content. Users of the application are unhappy if this degraded mode occurs too frequently, but they would rather have some content served instead of no content at all. You want to set a Service Level Objective (SLO) to ensure that the user experience does not degrade too much. What Service Level Indicator (SLI) should you use to measure this?

Answer options

• A. A quality SLI: the ratio of non-degraded responses to total responses.
• B. An availability SLI: the ratio of healthy microservices to the total number of microservices.
• C. A freshness SLI: the proportion of widgets that have been updated within the last 10 minutes.
• D. A latency SLI: the ratio of microservice calls that complete in under 100 ms to the total number of microservice calls.

Correct answer: A

Explanation

The correct answer is A because measuring the quality of responses by tracking the ratio of non-degraded responses to total responses directly addresses user satisfaction with the content served. Options B, C, and D focus on different aspects of service performance that do not specifically measure the user experience regarding content availability, which is the main concern in this scenario.